Constitutive Relation Study Of Viscoelastic Damping Materials Under Complex Conditions And Optimization Design Of Damping Structures

Under complex conditions, the static and dynamical mechanical behaviors of viscoelastic damping material ZN-17 and ZN-33 are studied experimentally and theoretically. Simultaneously optimization design of three damping structure are conducted.The main contents are as follows:(1) The dynamic sweeping tests under broad temperature, broad frequency and broad dynamic displacement are conducted to investigate the dynamic damping properties for two materials. Based on experimental datum, the mathematical expressions of the complex compliance are obtained by using the nonlinear fitting method. Error analyses show the validity of the expressions.(2) By using several classical viscoelastic models, the predication capabilities on the frequency response behavior are evaluated for two materials. Based on the RT model, a M-RT modified model is proposed in which the influences of temperature, frequency and dynamic displacement are considered. Comparing with the experimental results, the suggested model can characterize better the dynamic constitutive behavior of the materials under broad temperature, broad frequency and broad dynamic displacement.(3) The creep tests of two materials are carried out under different temperatures and different loadings. Several classic viscoelastic models are adopted to predict the creep curves of the materials. Predicted results show that the linear models can describe approximately the creep curves of ZN-33, however can't describe the creep behavior of ZN-17 due to its strongly nonlinear creep characters.(4) The time-stress equivalence principle and the nonlinear creep model proposed are applied to describe the nonlinear creep behaviors of ZN-17 respectively. Analyses and comparison show that the nonlinear creep behaviors of ZN-17 can be described comprehensively by using the proposed nonlinear creep model.(5) Based on the vibration experiments on three damping structures, the finite element model including variable parameters is established. Numerical simulations on the structures are conducted under different geometric and different material parameters with Nastran software. A series of resonance frequencies and structural loss factors of the damping structures are obtained. The parametric fitting expressions of the resonance frequencies and structural loss factors with geometric and material parameters of the structures are established by using nonlinear numerical fitting analysis. Founded on sensitivity theory, an optimization design method of the structures is. proposed and is successfully applied to the optimization design of three damping structures.(6) Accordng to the optimization design method, Optimization design software of three damping structures are established by the aid of Delphi. The structures are optimized rapidly and effectively by the software.